Systems are known that make use of liquids enriched with a gas. For example, U.S. Pat. No. 2,713,026 to Kelly et al. appears to disclose the use of a gas-enriched fluid for wastewater treatment, and in particular the introduction of an air-supersaturated fluid into a pool of wastewater to suspend solids in the wastewater and facilitate their removal. Another example is U.S. Pat. No. 4,192,742 to Bernard et al., which appears to teach that the biodegradation of wastewater can be promoted by treating the wastewater within a treatment chamber maintained at a pressure above atmospheric pressure to achieve super oxygenation of the wastewater.
Methods and equipment for enriching a liquid with a gas are also known. For example, U.S. Pat. No. 3,957,585 to Malick appears to disclose that atomized liquid can be introduced into a reaction zone to effect intimate contact of the atomized liquid with a gas phase. A particular type of atomizing spray head for this purpose is disclosed in U.S. patent application Ser. No. 13/602,793 to Eppink et al., filed Sep. 4, 2012, whose contents are fully incorporated herein by reference (“Eppink”). As explained in Eppink, such spray heads are adapted to introduce an atomized fluid (for example, potable water or sewage water) into a chamber containing oxygen at a high pressure, with the result that the fluid becomes saturated with oxygen. The oxygen-saturated fluid can then be introduced into a stream of wastewater with the result that the wastewater contains sufficiently high levels of oxygen to promote the activity of aerobic microorganisms capable of biodegrading waste in the wastewater.
U.S. Pat. Nos. 7,008,535 and 7,294,278, each to Spears et al., appear to disclose that a gas-supersaturated fluid can be introduced into a wastewater so that the gas-supersaturated liquid is introduced in a substantially bubble-free manner. For this purpose, Spears discloses the use of one or more fluid exit nozzles containing capillaries through which the gas-supersaturated liquid can be injected into the wastewater. U.S. Pat. No. 7,294,278 to Spears et al. discloses capillaries having diameters of about 150 to about 450 micrometers in nozzles having a plate-like construction, and capillary diameters of about 0.005 inch (about 125 micrometers) in nozzles having a more conventional spray head-type configuration. A drawback of the capillaries is that they may be prone to becoming plugged by solids and reaction products that may be entrained within the gas-supersaturated fluid.